content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf;
  
  import java.io.IOException;
  
  /**
   * This class is used internally by the Protocol Buffer library and generated
   * message implementations.  It is public only because those generated messages
   * do not reside in the {@code protobuf} package.  Others should not use this
   * class directly.
   *
   * This class contains constants and helper functions useful for dealing with
   * the Protocol Buffer wire format.
   *
   * @author kenton@google.com Kenton Varda
   */
  public final class WireFormat {
    // Do not allow instantiation.
    private WireFormat() {}
  
    static final int FIXED32_SIZE = 4;
    static final int FIXED64_SIZE = 8;
    static final int MAX_VARINT32_SIZE = 5;
    static final int MAX_VARINT64_SIZE = 10;
    static final int MAX_VARINT_SIZE = 10;
  
    public static final int WIRETYPE_VARINT           = 0;
    public static final int WIRETYPE_FIXED64          = 1;
    public static final int WIRETYPE_LENGTH_DELIMITED = 2;
    public static final int WIRETYPE_START_GROUP      = 3;
    public static final int WIRETYPE_END_GROUP        = 4;
    public static final int WIRETYPE_FIXED32          = 5;
  
    static final int TAG_TYPE_BITS = 3;
    static final int TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1;
  
    /** Given a tag value, determines the wire type (the lower 3 bits). */
    public static int getTagWireType(final int tag) {
      return tag & TAG_TYPE_MASK;
    }
  
    /** Given a tag value, determines the field number (the upper 29 bits). */
    public static int getTagFieldNumber(final int tag) {
      return tag >>> TAG_TYPE_BITS;
    }
  
    /** Makes a tag value given a field number and wire type. */
    static int makeTag(final int fieldNumber, final int wireType) {
      return (fieldNumber << TAG_TYPE_BITS) | wireType;
    }
  
    /**
     * Lite equivalent to {@link Descriptors.FieldDescriptor.JavaType}.  This is
     * only here to support the lite runtime and should not be used by users.
     */
    public enum JavaType {
      INT(0),
      LONG(0L),
      FLOAT(0F),
      DOUBLE(0D),
      BOOLEAN(false),
      STRING(""),
      BYTE_STRING(ByteString.EMPTY),
      ENUM(null),
      MESSAGE(null);
  
      JavaType(final Object defaultDefault) {
        this.defaultDefault = defaultDefault;
      }
  
      /**
       * The default default value for fields of this type, if it's a primitive
       * type.
       */
      Object getDefaultDefault() {
        return defaultDefault;
      }
  
      private final Object defaultDefault;
    }
  
    /**
     * Lite equivalent to {@link Descriptors.FieldDescriptor.Type}.  This is
     * only here to support the lite runtime and should not be used by users.
     */
    public enum FieldType {
      DOUBLE  (JavaType.DOUBLE     , WIRETYPE_FIXED64         ),
      FLOAT   (JavaType.FLOAT      , WIRETYPE_FIXED32         ),
      INT64   (JavaType.LONG       , WIRETYPE_VARINT          ),
      UINT64  (JavaType.LONG       , WIRETYPE_VARINT          ),
      INT32   (JavaType.INT        , WIRETYPE_VARINT          ),
      FIXED64 (JavaType.LONG       , WIRETYPE_FIXED64         ),
      FIXED32 (JavaType.INT        , WIRETYPE_FIXED32         ),
      BOOL    (JavaType.BOOLEAN    , WIRETYPE_VARINT          ),
      STRING  (JavaType.STRING     , WIRETYPE_LENGTH_DELIMITED) {
        @Override
        public boolean isPackable() {
          return false; }
      },
      GROUP   (JavaType.MESSAGE    , WIRETYPE_START_GROUP     ) {
        @Override
        public boolean isPackable() {
          return false; }
      },
      MESSAGE (JavaType.MESSAGE    , WIRETYPE_LENGTH_DELIMITED) {
        @Override
        public boolean isPackable() {
          return false; }
      },
      BYTES   (JavaType.BYTE_STRING, WIRETYPE_LENGTH_DELIMITED) {
        @Override
        public boolean isPackable() {
          return false; }
      },
      UINT32  (JavaType.INT        , WIRETYPE_VARINT          ),
      ENUM    (JavaType.ENUM       , WIRETYPE_VARINT          ),
      SFIXED32(JavaType.INT        , WIRETYPE_FIXED32         ),
      SFIXED64(JavaType.LONG       , WIRETYPE_FIXED64         ),
      SINT32  (JavaType.INT        , WIRETYPE_VARINT          ),
      SINT64  (JavaType.LONG       , WIRETYPE_VARINT          );
  
      FieldType(final JavaType javaType, final int wireType) {
        this.javaType = javaType;
        this.wireType = wireType;
      }
  
      private final JavaType javaType;
      private final int wireType;
  
      public JavaType getJavaType() { return javaType; }
      public int getWireType() { return wireType; }
  
      public boolean isPackable() { return true; }
    }
  
    // Field numbers for fields in MessageSet wire format.
    static final int MESSAGE_SET_ITEM    = 1;
    static final int MESSAGE_SET_TYPE_ID = 2;
    static final int MESSAGE_SET_MESSAGE = 3;
  
    // Tag numbers.
    static final int MESSAGE_SET_ITEM_TAG =
      makeTag(MESSAGE_SET_ITEM, WIRETYPE_START_GROUP);
    static final int MESSAGE_SET_ITEM_END_TAG =
      makeTag(MESSAGE_SET_ITEM, WIRETYPE_END_GROUP);
    static final int MESSAGE_SET_TYPE_ID_TAG =
      makeTag(MESSAGE_SET_TYPE_ID, WIRETYPE_VARINT);
    static final int MESSAGE_SET_MESSAGE_TAG =
      makeTag(MESSAGE_SET_MESSAGE, WIRETYPE_LENGTH_DELIMITED);
  
    /**
     * Validation level for handling incoming string field data which potentially
     * contain non-UTF8 bytes.
     */
    enum Utf8Validation {
      /** Eagerly parses to String; silently accepts invalid UTF8 bytes. */
      LOOSE {
        @Override
        Object readString(CodedInputStream input) throws IOException {
          return input.readString();
        }
      },
      /** Eagerly parses to String; throws an IOException on invalid bytes. */
      STRICT {
        @Override
        Object readString(CodedInputStream input) throws IOException {
          return input.readStringRequireUtf8();
        }
      },
      /** Keep data as ByteString; validation/conversion to String is lazy. */
      LAZY {
        @Override
        Object readString(CodedInputStream input) throws IOException {
          return input.readBytes();
        }
      };
  
      /** Read a string field from the input with the proper UTF8 validation. */
      abstract Object readString(CodedInputStream input) throws IOException;
    }
  
    /**
     * Read a field of any primitive type for immutable messages from a
     * CodedInputStream. Enums, groups, and embedded messages are not handled by
     * this method.
     *
     * @param input The stream from which to read.
     * @param type Declared type of the field.
     * @param utf8Validation Different string UTF8 validation level for handling
     *                       string fields.
     * @return An object representing the field's value, of the exact
     *         type which would be returned by
     *         {@link Message#getField(Descriptors.FieldDescriptor)} for
     *         this field.
     */
    static Object readPrimitiveField(
        CodedInputStream input,
        FieldType type,
        Utf8Validation utf8Validation) throws IOException {
      switch (type) {
        case DOUBLE  : return input.readDouble  ();
        case FLOAT   : return input.readFloat   ();
        case INT64   : return input.readInt64   ();
        case UINT64  : return input.readUInt64  ();
        case INT32   : return input.readInt32   ();
        case FIXED64 : return input.readFixed64 ();
        case FIXED32 : return input.readFixed32 ();
        case BOOL    : return input.readBool    ();
        case BYTES   : return input.readBytes   ();
        case UINT32  : return input.readUInt32  ();
        case SFIXED32: return input.readSFixed32();
        case SFIXED64: return input.readSFixed64();
        case SINT32  : return input.readSInt32  ();
        case SINT64  : return input.readSInt64  ();
  
        case STRING  : return utf8Validation.readString(input);
        case GROUP:
          throw new IllegalArgumentException(
            "readPrimitiveField() cannot handle nested groups.");
        case MESSAGE:
          throw new IllegalArgumentException(
            "readPrimitiveField() cannot handle embedded messages.");
        case ENUM:
          // We don't handle enums because we don't know what to do if the
          // value is not recognized.
          throw new IllegalArgumentException(
            "readPrimitiveField() cannot handle enums.");
      }
  
      throw new RuntimeException(
        "There is no way to get here, but the compiler thinks otherwise.");
    }
  }
  